The present invention relates generally to the field of electrophotographic image forming, and more particularly to a seal design for cleaning assemblies of electrophotographic image forming apparatuses that helps prevent toner leakage.
In the electrophotographic printing process, an image forming apparatus, such as a laser printer, selectively exposes a uniformly charged image carrier known as a photoconductor to form a latent image. The latent image is made visible by toner, and the toner image is transferred to a recording medium so that the image may be rendered permanent. In such an apparatus, additional toner must be supplied each time the toner is used up, which may be inconvenient and messy. Also, the presence of toner outside its intended areas may make it necessary to perform maintenance on various parts of the apparatus. As such, significant emphasis is placed on preventing leakage of toner outside its intended areas in the electrophotographic printing process.
The present invention is directed to an end seal design that uses an array of ridges (or grooves) to urge toner inwardly so as to help prevent outward toner escape, and to cleaning assemblies in an electrophotographic image forming apparatus that employ such an end seal design. Because the end seal according to the present invention does more than merely create a passive barrier to toner, it also actively urges toner in the desired direction, the end seal may be referred to herein as a dynamic end seal.
In a first aspect of the invention, the inventive concept is used on an end seal for a cleaning assembly associated with a photoconductor, such as a common photoconductive drum. The cleaning assembly includes a photoconductive drum, a cleaning blade, one or more end seals, and an optional lower flexible seal. The end seals include a blade pocket for mating with the end portions of the cleaning blade and another portion having an array of ridges thereon. The ridges are angled inward and, when in contact with the photoconductive drum, urge any toner trapped therebetween inward towards the center of the photoconductive drum, where the toner can be directed to a waste reservoir in a normal fashion. This xe2x80x9csnowplowingxe2x80x9d action of the ridges helps prevent outward migration of the toner, thereby minimizing toner escape. The end seal may be composed of two layersxe2x80x94the layer closest to the photoconductive drum being a relatively firm low friction material, while the layer away from the photoconductive drum being compliant material such as foam. The compliant material helps bias the end seal against the photoconductive drum, the cleaning blade, and the lower flexible seal, and account for surface variations in the nearby housing. There may be, of course, one such end seal at each end of the cleaner blade.
In a second aspect of the invention, the inventive concept is used on an end seal for a cleaning assembly associated with an intermediate transfer medium, such as an intermediate transfer belt. The cleaning assembly includes an intermediate transfer medium, a cleaning blade, one or more end seals, and an optional lower flexible seal. The end seals include a blade pocket for mating with the end portions of the cleaning blade and another portion having an array of ridges thereon. The ridges are angled inward and, when in contact the intermediate transfer medium, urge any toner trapped therebetween inward towards the center of the intermediate transfer medium, where the toner can be directed to a waste reservoir in a normal fashion. This xe2x80x9csnowplowingxe2x80x9d action of the ridges helps prevent outward migration of the toner, thereby minimizing toner escape. The end seal may be composed of two layersxe2x80x94the layer closest to the intermediate transfer medium being a relatively firm low friction material, while the layer away from the intermediate transfer medium being compliant material such as foam. The compliant material helps bias the end seal against the intermediate transfer medium, the cleaning blade, and the lower flexible seal, and account for surface variations in the nearby housing. There may be, of course, one end seal at each end of the relevant cleaner blade.